Summary

The identification of two genes, BRCA1 and BRCA2, linked to hereditary breast and ovarian cancers raised hopes for improved prevention and treatment. But now that tests for mutations in these genes are coming on the market, reality is setting in. Too little is known about the mutations to give women carrying them a precise assessment of what they mean: Are these women almost certain to get cancer, or are the odds less grim? Clear answers will require huge studies on large numbers of women and their families, which are just beginning.